Molecules
Chemical Reactions: The Law of Conservation of Mass
Balancing Equations
Evidence of a Chemical Reaction
100
What doest he subscript mean after an atom?
What is the number of atoms of a particular element
100
If you are looking at the following chemical reaction, H + Cl → HCl What is(are) the reactants?
What are Hydrogen (H) and Chlorine (Cl)
100
What is the first step in balancing equations?
Write down what is given in the chemical reaction
100
Why are fireworks evidence of a chemical reaction?
They cause a color change
200
Define a molecule
A molecule is made up of more than one atom
200
Define a chemical reaction
A chemical reaction occurs when the bonds of a molecules break and new products are formed
200
How many Carbon (C), Oxygen (O) and Hydrogen (H) atoms are on the product side of the reaction? C10H8 + 12 O2 ---> 10 CO2 + 4 H2O
C = 10 O = 24 H = 8
200
Describe a precipitate
A solid that forms after a chemical reaction occurs
300
What does it mean if there is a coefficient in front of a molecules Example: 4HCl
It means that there are 4 HCl molecules.
300
Describe why dissolving salt in water is not considered a chemical reaction?
There are no new products formed. If you evaporate the water, salt will be left over.
300
Balance the following equation: H + Cl2 = HCl
2H + Cl2 = 2HCl
300
Describe why part 2 of our experiment supported the law of conservation of mass better than part 1.
The gas that was formed was trapped in the plastic bag. The mass was accounted for.
400
What is a bond?
A bond holds different atoms together in a molecule
400
Define the law of conservation of mass
What is matter can neither be created nor destroyed
400
Describe why a chemical reaction must be balanced
The law of conservation of mass states that matter can neither be created nor destroyed
400
What are the four different types of evidence that prove a chemical reaction has occurred?
1. formation of a gas 2. formation of a precipitate 3. color change 4. temperature change
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